But when it comes to sensor size, not all stand-alone digital cameras are created equal. A special class—known as a full-frame camera—has a mammoth sensor, one that’s the same size as a frame of 35mm film. This is considerably larger than what’s found in smartphones and the majority of digital cameras.

Pros have been using full-frame models for years, but even casual photographers can appreciate the improved performance these devices offer. Full-frame cameras are better at shooting in low light. And their photos are typically more detailed and remain sharp even when you enlarge them to fill a computer screen or make prints to hang on a wall.

The main drawback of full-frame cameras has long been cost. You had to be obsessive about the quality of your shots to consider purchasing one. But those who are ready to make the leap are in luck. As camera-makers scramble to find new ways to lure consumers away from their phones, prices of these once top-end options have been dropping. And although earlier models were so bulky that only a pro could justify lugging one around, you can now find ones that are remarkably compact.

Here are three worth adding to your market-research shortlist.

For Optics: Leica SL

Photo:
F. Martin Ramin/The Wall Street Journal

Yes, the cost of a Leica SL creeps into five-figure territory when you factor in the cost of a lens. And yes, this camera is also somewhat of a beast, its body alone weighing over 2.5 pounds.

But for many hard-core enthusiasts, the optics make the SL’s price and size all worth it. Leica lenses have long been considered among the best you can get. This new model, out Nov. 16, is compatible with any of the 145 interchangeable lenses the company currently offers—as well as the new zoom lens Leica will launch with this camera and the two new lenses slated to be introduced next year.

The SL has many other pro-friendly features: It can record higher-than-high-def 4K video, for example. And it fires off shots at a remarkable clip—11 photos per second at its full, 24-megapixel resolution.

For many fans, however, the joy of using an SL is as much about aesthetics and feel as performance—the way its frame is machined from a single slab of aluminum, right down to the textured, right-hand grip. No other camera feels quite like it. $7,495 for body, $12,445 including the lens shown, en.leica-camera.com

For Compactness: Sony RX1R ii

Photo:
F. Martin Ramin/The Wall Street Journal

The release of the original RX1, back in 2012, brought full-frame cameras firmly into the mainstream. The camera was revolutionary at the time: A full-frame model small enough to fit in your palm—but priced thousands of dollars less than Leica’s competing compact full-frame camera, the M9.

Three years and multiple upgrades later, the RX1R ii, available later this month, is even more of a powerhouse, with a big bump in megapixels (up to 42) and a pop-up electronic view finder that should come in handy when shooting in direct sunlight (which would otherwise wash out the camera’s 3-inch display). Thanks to an upgraded autofocus system that scans an image area with more detection points than most DSLRs, the RX1R ii is more responsive than its predecessors, too.

But of all its impressive stats, the one most amateur photographers will probably value is its maximum native ISO rating—a measure of how well the camera can shoot in dark environments without sacrificing image quality. The RX1Rii goes up to a whopping 25600 ISO—which means you’ll be able to snap crisp, candid shots without having to use a mood-killing flash. $3,300, sony.com

For Price: Nikon D750

Photo:
F. Martin Ramin/The Wall Street Journal

If such a thing as an “entry level” full-frame camera exists, this winning model is it. Like a traditional interchangeable-lens DSLR, the D750 shoots quickly, even in relatively dark scenarios. But its numbers can’t quite compete with the Leica and
Sony
models shown here. Though it burst-shoots more than six frames per second at full 24-megapixel resolution, that’s considerably slower than the Leica. And its functional ISO ceiling of 12800, while still extremely impressive, pales in comparison to the Sony.

What makes the D750 worth considering, especially for those just getting into the full-frame game, is its price. Since the camera’s introduction last year, the cost has dropped considerably.

Because
Nikon
hasn’t radically changed its lens mount since the 1970s, the D750 is compatible with hundreds of classic SLR lenses from the company. Which means you can save money by either dusting off that lens you haven’t used since college, or by searching the Internet for a used one. (With really old lenses, autofocus and other features might not work.) The D750, in other words, proves that full-frame doesn’t have to be full-price. $1,900 for body, $2,400 with lens shown, nikonusa.com